VMS Help RTL Routines, MTH$, MTH$CVT x x, Returns  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    OpenVMS usage:floating_point
    type:         G_floating, D_floating
    access:       write only
    mechanism:    by value

    The converted value. MTH$CVT_D_G returns a G-floating value.
    MTH$CVT_G_D returns a D-floating value.